Printing telegraph



Aug. 6,19 0- A. E. THOMPSON ET AL PRINTING TELEGRAPH Filed Jan. 7, 1937 2 Sheets-Sheet 1 D/JTE/BUTOR FOQ CONTROLLING CONT/467$ l?- D. 541 MO/V BY ATTORNEY 8-. 6, 1940- A. E. THOMPSON ET AL 2.210.641

PRINTING TELEGRAIH 2 Sheets-Sheet 2 Filed Jan. 7. 19:57

U M N v& moas N 45. THOMPSo/V ATTORNEY Patented Aug. 6, 1940 UNlTtlB ATEN-l" PRINTING TELEGRAPH Alfred Edward Thompson and Reginald Dennis Salmon, Croydon, England, assignors to Creed and Uompany Limited, Croydon, Surrey, England Application January 7, 1937, Serial No. 119,438

In Great Britain January 31, 1936 2 Claims.

This invention relates to type printing telegraph systems and apparatus.

Type printing telegraph apparatus working on the start-stop principle has been for some time I moving at high speed and consequently noisy operation and considerable wear and maint nance. Apparatus working with. multiple magnets on the start-stop principle is, of course, known but its use has previously involved elaborate-distributing arrangements, and for this reason it is not now used for start stop working despite its avoidance of the disadvantages above referred to. It continues to be used for multiplex operation,.since ample time is left in multiplex systems to enable the selecting. and printing operations to be performed comparatively slowly.

It is the object of the present invention to provide a simple form of distributing arrangement and a multi-magnet printing telegraph apparatus that is adaptable for use with both startstop and multiplex systems.

According to the invention a line circuit is connected through contacts closed only for a brief period in the middle of each signal element so as to apply the signal potential between the grid and cathode of a grid controlled gas filled tube, and the currents in the anode circuit of such tube are distributed to the magnets of avmultimagnet printer.

The nature of the invention will be better understood from the following description taken in conjunction with the accompanying drawings in which: 1

Fig. 1 shows diagrammatically a circuit arrangement according to the invention; and

Fig. 2 shows a multi-magnet translator arrangement.

Referring now to Fig. 1, a resistance 3 matching the impedance of the signalling line is connected across the terminals l, 2 of the line. The resistance 3 is connected to a high impedance t which, with a suitable biassing battery is connected between the grid and cathode of a gas filled thermionic tube 5.

A switch 6 is interposed in the connection between resistance 3 and impedance i for making and breaking the connection. The arrangement shown is adapted for start-stop operation on a six-unit code, and in consequence the anode of the tube is connected through contacts 7A 1G respectively to seven relays IZA IZG,

battery it, and contacts 8 to the cathode of the tube. Since distributors for controlling telegraph arrangements are known in the prior art the particular form. of distributor forms no part of this invention, the distributor is shown 5 merely in block diagram with the contact controls and the start control indicated by broken lines connected to the distributor.

Contacts 6, IA 16,3 and 9 (described herem after) are operated in correct sequence in known 10 manner by means of cams mounted upon a common shaft. This shaft tends to be continuously driven from a motor through, a clutch in a manner well known in printing telegraph apparatus but is held stationary by a detent under control of relay 82G. Contacts t and 5G and 8 are closed in the stationary position of the shaft. The arrival of a start impulse impresses suiiicient positive potential on the grid of tube 5 to overcome the normal biassing potential and initiates a discharge therein. Relay I2G operates and removes the detent holding the cam shaft from rotation and the shaft begins to rotate. Immediately after commencement of rotation contacts 6 and K3 open. Thereafter contacts 6 are closed for a brief period in the middle of each signal element and contacts lA (F are closed seriatim, one being opened before the next one closes. Impulses of marking potential initiate a discharge in the tube 5 and the corresponding relay of the relays lA 1F are operated. The operated relays close their respective locking contacts IDA lllF and also contacts HA HF. After the receipt of the last signal contacts 9 close and the magnets l3A ing to the operated relays are operated and set the translating mechanism of the printer and cause printing to take place in any well known manner. Just before the cam shaft comes to rest contacts 8 are opened momentarily to de-ener- 40 gise all the relays IZA IZF and as the shaft comes to rest contacts 6, 1G and 8 are reclosed.

The above arrangement will operate with either direct current impulses or voice frequency impulses in the line. tive signals will initate a discharge in the tube 5, and in the latter no current intervals Will be ineffective, but a single cycle of voice frequency current will be sufficient to initiate a discharge.

Any suitable form of translating mechanism may be operated by the magnets I3A I3F but in order to eliminate unnecessary noise and unnecessary wear of mechanical parts it is desirable that a type lever or the position of a type wheel should be selected by means of an aggregate l3F correspond- 35 In the former case only posi- 45 motion system. A suitable form of such system is shown in Fig. 2. A gear wheel I5 attached to the type wheel is rotated by means of a rack 33 actuated by an aggregate motion system comprising linked levers l6, l1 and it. These levers are shown for clearness of illustration as connected by links l9 and 20 but in practice they would be arranged as described and claimed in British Patent No. 443,231. These levers are actuated at points intermediate their ends by means of the respective magnets IBA, I33 and MC. As shown in the drawing three magnets only are shown. The remaining three magnets may actuate a similar lever system for positioning the type wheel in another direction, that is, one set of three magnets may select a row of characters on the type wheel, and the other set a character in the selected row. Or all six magnets may act upon a single aggregate motion system of six levers. Or five magnets may act upon an aggregate motion system of five levers and the sixth magnet serve to select directly a row of characters on the type wheel. In this last case the sixth impulse would be in the nature of a case shift signal.

The armature of each of the magnets I3A, BB and ISO is linked to a toothed segment 24, or 26 meshing with a gear wheel 21', 28 or 29. Attached to the respective gear wheels 21, 28 or 29 are disks carrying eccentric pins 30, 3| or 32 connected by links 21, 22 or 23 with the respective levers I6, I! or 18. The segments and gear wheels are arranged so that the attraction or falling back of the armature of any magnet moves the corresponding gear wheel through half a revolution, the eccentric pins 30, 3| and 32 being so placed that they are at rest in positions in which any reaction from the link is taken on the dead centre thus avoiding any reaction from the type wheel reaching the magnet armature. Moreover, the positioning of the type wheel is effected in this manner with the minimum degree of bounce because the motion imparted by each magnet through the eccentric pin tends to approximate to harmonic motion.

What is claimed is:

1. A printing telegraph receiving system comprising a line, a grid controlled gas discharge tube, means for deriving potentials from said line and for impressing said potentials on the grid circuit of said grid controlled gas discharge tube during a brief portion of each signal element period, a series of relays or magnets, a single distributor and contacts on said distributor for connecting the grid circuit of said tube to said line, and other contacts on said distributor for connecting said series of relays or magnets in turn to the anode circuit of said tube, means for normally holding said distributor at rest with the grid circuit of said tube connected to said line, a start relay for said distributor normally connected in the anode circuit of said tube, a multiple magnet printer the respective magnets of which are controlled by said relays or magnets, and means for interrupting said anode circuit during times at which the line potentials are ineffective upon the grid circuit of said tube.

2. A printing telegraph receiving system comprising a line, a grid controlled gas discharge tube, means for deriving potentials from said line corresponding to a signal element period and for impressing said potentials on the grid circuit of said grid controlled gas discharge tube during a brief portion of each signal element period, a series of relays, one for each signal element, locking contacts for said relays, means for connecting said relays in turn in the anode circuit of said tube, means for rendering all said relays simultaneously effective to operate the magnets of a multi-magnet printer, and means for interrupting said anode circuit during times at which the line potentials are inefiective upon the grid circuit of said tube.

ALFRED EDWARD THOMPSON.

REGINALD DENNIS SALMON. 

